JP2017161024A - Sealing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the enlargement of a contact area between a seal lip and a shaft.SOLUTION: A sealing device comprises an annular reinforcing ring 2, and an annular elastic body part 3. The elastic body part 3 has: an annular seal lip 32 having a lip main body part extending in a direction along an axial line x, and a lip tip part which is formed at the lip main body part so as to slidably contact with an external peripheral face 120a of a shaft 120 being a sealing object; and an annular protrusion 33 which is arranged adjacent to the seal lip 32, and protruded in a direction along the axial line x. A ceiling portion of the protrusion 33 is warped via a neck portion, a part of the ceiling portion abuts on a back face of the lip main body part being a back side of the lip tip part, and an annular space is formed. By this constitution, the back face of the lip main body part is concealed by the ceiling portion, and the application of hydraulic pressure on the back face can be avoided, thus suppressing the enlargement of a contact area between the seal lip 32 and the external peripheral face 120a of the shaft 120.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a sealing device, and more particularly to a sealing device mounted on a hydraulic shock absorber (shock absorber) of an automobile or a motorcycle.

  Conventionally, shock absorbers, particularly single cylinder shock absorbers, are divided into an oil chamber and a gas chamber by a free piston in one cylinder, and the piston rod moves through the oil chamber and enters the oil chamber. The oil corresponding to the volume of the piston rod depresses the free piston and compresses the gas chamber to generate a damping force.

  In such a single-cylinder shock absorber, a sealing device for sealing the outer peripheral surface of the piston rod and preventing leakage of hydraulic oil inside the cylinder from the outer peripheral surface of the piston rod is mounted. .

  As shown in FIGS. 4 and 5, the conventional sealing device 100 includes a reinforcing ring 103, a seal lip portion 101 formed integrally with the reinforcing ring 103, and a dust lip portion 102 formed integrally with the reinforcing ring 103. It has.

  The reinforcing ring 103 is made of a metal annular member, and a crimping portion 110a formed by bending an opening end of a cylinder 110 of a single-cylinder shock absorber is present on the side to be sealed (in the direction of arrow a) with respect to the crimping portion 110a. It is sandwiched between the rod guide 115.

  The seal lip portion 101 is a portion integrally formed so as to cover the end surface 103a on the sealing object side (arrow a direction) of the reinforcing ring 103, and has an outer peripheral lip 101a and an inner peripheral lip 101b. The outer peripheral lip 101 a is a portion that seals between the inner peripheral surface 110 a of the cylinder 110 and the outer peripheral surface 115 a of the rod guide 115. The inner peripheral lip 101b is a lip portion that is slidably liquid-contacted with the outer peripheral surface 120a of the piston rod 120 when the sealing device 100 is mounted.

  The dust lip portion 102 is a portion that is integrally formed so as to cover the end surface 103 b on the atmosphere side (arrow b direction) of the reinforcing ring 103. The dust lip portion 102 is provided on the atmosphere side (in the direction of the arrow b) with respect to the seal lip portion 101, and is a lip portion that is slidably and liquid-tightly contacted with the outer peripheral surface 120a of the piston rod 120 when the sealing device 100 is mounted. It is.

  When the sealing device 100 having such a configuration is mounted between the cylinder 110 and the piston rod 120, the inner peripheral lip 101a of the seal lip 101 contacts the outer peripheral surface 120a of the piston rod 120 with an appropriate tightening allowance. Is done. Thereby, the sealing device 100 prevents the hydraulic oil inside the cylinder 110 from flowing out from the outer peripheral surface 120a of the piston rod 120 to the atmosphere side (arrow b direction).

  However, in recent years, in the single-cylinder shock absorber, the hydraulic pressure F of the hydraulic oil inside the cylinder 110 is applied to the back surface portion including the inclined slope of the inner peripheral lip 101a as the sealed pressure of the high-pressure gas increases. As a result, the component force Fa in the direction parallel to the back surface portion (slope surface) acts, and at the same time, the component force Fb in the direction perpendicular to the back surface portion (slope surface) acts.

  Due to the presence of this component force Fb, the inner peripheral lip 101a is pressed against the outer peripheral surface 120a of the piston rod 120, the contact area between the inner peripheral lip 101a and the outer peripheral surface 120a of the piston rod 120 increases, and the inner peripheral side The tightening force of the lip 101a increases. As a result, the contact portion where the tightening force of the inner peripheral lip 101a is increased is rubbed due to friction, so-called dripping wear occurs, and the sealing performance of the sealing device 100 is unstable.

  In view of this, a sealing device in which a backup ring is added to the seal lip portion 101 has been proposed as a countermeasure for preventing the occurrence of such wear (see, for example, Patent Document 1).

  As shown in FIG. 6, the sealing device 150 includes reinforcing rings 151 and 153 made of a metal annular member, a seal lip portion 152 formed integrally with the reinforcing ring 151, and a dust lip portion 156 formed integrally with the reinforcing ring 153. And a backup ring 160 attached to the inner peripheral side (in the direction of arrow d) of the seal lip 152.

  The seal lip 152 is integrally formed so as to cover the reinforcing ring 151 from the side to be sealed (in the direction of the arrow a), and contacts an inner peripheral surface of a cylinder (not shown) and seals the outer peripheral side seal lip 152a. An inner peripheral side seal lip 152b that seals in contact with the outer peripheral surface is provided.

  On the inner peripheral side (arrow d direction) end surface of the inner peripheral seal lip 152b, a wedge-shaped annular lip tip 152bs whose shape in the cross section along the axis x is convex toward the inner peripheral side (arrow d direction). Is formed. A garter spring 154 that applies a biasing force for pressing the lip tip 152bs against the outer peripheral surface of the piston rod is mounted in a recess formed in the back surface of the outer peripheral side (in the direction of arrow c) of the inner peripheral seal lip 152b. ing.

  The backup ring 160 is disposed in an annular recess formed on the inner peripheral side (arrow d direction) of the inner peripheral seal lip 152b and on the atmosphere side (arrow b direction) from the lip tip 152bs. It is mounted in a state of being sandwiched between the peripheral side seal lip 152b and the end surface of the reinforcing ring 153 on the sealing target side (arrow a direction).

  Therefore, even if the inner peripheral lip 152b is pressed against the outer peripheral surface of the piston rod by the hydraulic pressure of the hydraulic oil in the cylinder, the inner peripheral surface of the backup ring 160 is brought into contact with the outer peripheral surface of the piston rod. As described above, the inner peripheral lip 152b is not pressed against the outer peripheral surface of the piston rod. For this reason, it is suppressed that the contact area of the inner peripheral side lip 152b and the outer peripheral surface of a piston rod increases.

JP 2008-309263 A

  However, according to the sealing device 150 of Patent Document 1 described above, an increase in the contact area between the inner peripheral lip 152b and the outer peripheral surface of the piston rod can be effectively suppressed by the backup ring 160. Since the ring 160 is added, the number of parts is increased, the structure is complicated, and the manufacturing cost is increased.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a sealing device with a simple configuration and low cost that can suppress an increase in the contact area between the seal lip and the shaft.

  In order to achieve the above object, a sealing device according to the present invention is an elastic body comprising an annular reinforcing ring centered on an axis and an annular elastic body centered on the axis and integrally formed with the reinforcing ring. A lip body portion extending in a direction along the axis, and a lip formed on the lip body portion so as to slidably contact the outer peripheral surface of the shaft to be sealed. An annular seal lip having a tip portion, and an annular projection provided adjacent to the seal lip and projecting in a direction along the axis, the projection being orthogonal to the axis A ceiling portion parallel to the direction and having a flat ceiling surface; and a neck portion formed to support the ceiling portion in a direction along the axis and bendable in a direction perpendicular to the axis. And the ceiling portion of the protrusion is When pressed toward the outer peripheral surface, the ceiling portion bends in a direction perpendicular to the axis via the neck portion, and the ceiling portion is partly behind the lip tip portion. An annular space is formed in contact with the back surface of the main body.

  In the sealing device according to an aspect of the present invention, when the annular space is formed, a back surface portion of the lip body is concealed by the ceiling portion.

  In the sealing device according to an aspect of the present invention, the elastic body portion includes a dust lip provided on the atmosphere side of the seal lip so as to be slidably in contact with the outer peripheral surface of the shaft. And

  ADVANTAGE OF THE INVENTION According to this invention, the simple structure which can suppress the increase in the contact area of a seal lip and a shaft, and a low-cost sealing device can be realized.

It is sectional drawing which shows the state with which the sealing device which concerns on embodiment of this invention was mounted | worn between a piston rod and a cylinder. It is an expanded sectional view showing composition of a sealing device concerning an embodiment of the invention. It is a partial expanded sectional view which shows a state when the projection part of the sealing device concerning embodiment of this invention and the back surface part of an inner peripheral side seal lip contact, and annular space is formed. It is sectional drawing which shows the state with which the conventional sealing device was mounted | worn between the piston rod and the cylinder. It is an expanded sectional view which shows the structure of the conventional sealing device. It is an expanded sectional view which shows the structure of the sealing device with which the conventional backup ring was mounted | worn.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view showing a state where a sealing device according to an embodiment of the present invention is mounted between a piston rod and a cylinder. FIG. 2 is an enlarged cross-sectional view showing the configuration of the sealing device according to the embodiment of the present invention. FIG. 3 is a partial enlarged cross-sectional view showing a state when the annular space is formed by contact between the protrusion of the sealing device according to the embodiment of the present invention and the back surface of the inner peripheral side seal lip.

  Hereinafter, for convenience of description, in FIGS. 1 to 3, in the arrow ab direction along the axis x (hereinafter, also referred to as “stroke direction”), the sealing target side is the arrow a along the axis x direction. And the atmosphere side is the direction of the arrow b along the axis x direction. That is, the sealing target side is the direction inside the cylinder 110 and facing the hydraulic oil. The atmosphere side is the direction outside the outer tube 120 and facing the atmosphere. In the direction of the arrow cd orthogonal to the axis x (hereinafter, also referred to as “radial direction”), the outer peripheral side is the arrow c direction away from the axis x, and the inner peripheral side is the arrow d approaching the axis x. The direction.

<Configuration of sealing device>
As shown in FIGS. 1 and 2, the sealing device 1 according to the embodiment of the present invention is mounted between the cylinder 110 and the piston rod 120, and in particular, the outer peripheral surface 120a of the piston rod 120 is sealed to provide the cylinder 110. This prevents the hydraulic fluid from leaking.

  The sealing device 1 includes an annular metal reinforcing ring 2 centered on the axis x and an elastic body portion 3 made of an annular elastic body centered on the axis x. The elastic body portion 3 covers the entire reinforcing ring 2 from the sealing target side (arrow a direction), the outer peripheral surface side (arrow c direction), the inner peripheral surface side (arrow d direction), and the atmosphere side (arrow d direction). So that they are attached together. However, the elastic body 3 completely covers the end surface 2a on the sealing object side (arrow a direction) of the reinforcing ring 2, but the inner surface of the end surface 2b on the atmosphere side (arrow b direction) of the reinforcing ring 2 It covers only a part of the side (arrow d direction).

  The reinforcing ring 2 is manufactured to have a rectangular cross section by, for example, pressing or forging, and the elastic body portion 3 is molded by cross-linking (vulcanization) molding using a molding die. At the time of this cross-linking molding, the reinforcing ring 2 is disposed in the mold, the elastic body portion 3 is bonded to the reinforcing ring 2 by cross-linking adhesion, and the elastic body portion 3 is molded integrally with the reinforcing ring 2. .

  Examples of the metal material of the reinforcing ring 2 include stainless steel and SPCC (cold rolled steel). Examples of the elastic body of the elastic body section 3 include various rubber materials. Examples of the various rubber materials include synthetic rubbers such as nitrile rubber (NBR), hydrogenated nitrile rubber (H-NBR), acrylic rubber (ACM), and fluorine rubber (FKM).

  The elastic body portion 3 is formed on the annular seal lip portion 4 that covers the reinforcing ring 2 from the sealing target side (arrow a direction) and on the atmosphere side (arrow b direction) from the seal lip portion 4. Is provided with an annular dust strip portion 5 that covers from the atmosphere side (arrow b direction).

  The seal lip 4 includes an outer peripheral lip 31, an inner peripheral lip 32, and a protrusion 33. The outer peripheral lip 31 is a lip portion that extends from the outer peripheral end (arrow c direction) end of the reinforcing ring 2 to the sealing target side (arrow a direction) in the stroke direction (arrow ab direction) along the axis x. A convex lip tip portion 31a that slidably contacts and seals with the inner peripheral surface 110a of the cylinder 110 is formed on the end surface of the outer peripheral lip 31 on the outer peripheral side (arrow c direction).

  The inner peripheral lip 32 as a seal lip extends from the inner peripheral side (arrow d direction) end of the reinforcing ring 2 to the sealing target side (arrow a direction) in the stroke direction (arrow ab direction) along the axis x. A lip body 321 and a lip tip 322 integrally formed on the inner peripheral side (in the direction of arrow d) of the lip body 321. The lip tip 322 is formed in an annular wedge shape whose shape in a cross section along the axis x is convex from the inner peripheral side (arrow d direction) end surface of the lip main body 321 toward the inner peripheral side (arrow d direction). ing.

  The lip main body portion 321 is continuous with the back surface 323 on the back side (outer peripheral side (arrow c direction)) of the lip tip portion 322, the lip tip portion 322, and the back surface 323, and in the radial direction (arrow cd direction). A parallel and flat ceiling surface 324 is provided. The back surface 323 is an inclined surface that is inclined toward the outer peripheral side (in the direction of arrow c) from the ceiling surface 324 toward the reinforcing ring 2.

  The protrusion 33 is formed between the outer peripheral lip 31 and the inner peripheral lip 32 and adjacent to the inner peripheral lip 32 at a position separated from the inner peripheral lip 32 by a predetermined distance. This is a protrusion-like portion protruding toward the sealing target side (arrow a direction) in the stroke direction (arrow ab direction) along the axis x.

  The protruding portion 33 includes a ceiling portion 331 and a neck portion 339. The ceiling portion 331 is an annular portion having a flat ceiling surface 332 that is parallel to the radial direction (arrow cd direction) orthogonal to the axis x.

  The protrusion 33 is parallel to the direction orthogonal to the ceiling surface 332, that is, the stroke direction along the axis x (arrow ab direction), and is an inner peripheral end surface (hereinafter referred to as “inner peripheral end surface”). 334, an end face on the outer peripheral side that is parallel and flat with the inner peripheral end face 334 (hereinafter also referred to as “outer peripheral end face”) 335, and an inclined face 336 that connects the ceiling face 332 and the outer peripheral end face 335. Have. The inclined surface 336 is formed in parallel to the inner peripheral inclined surface 116a of the convex portion 116 protruding in a trapezoidal shape protruding from the rod guide 115 (see FIG. 1) to the atmosphere side (arrow b direction).

  The neck portion 339 is an annular portion formed so that the ceiling portion 331 can be bent in a radial direction (arrow cd direction) orthogonal to the axis x, and supports the ceiling portion 335 in a direction along the axis x. Here, the neck portion 339 has an outer diameter D2 that is smaller than the outer diameter D1 of the ceiling portion 331 in the radial direction (arrow cd direction). As a result, an outer peripheral side constricted portion 33pg and an inner peripheral side constricted portion 33pi are formed between the ceiling portion 331 and the neck portion 339. The outer peripheral side constricted portion 33pg is formed to be largely constricted in a substantially semicircular shape toward the inner peripheral side (the direction of the arrow d). On the other hand, the inner peripheral side constricted portion 33pi is formed smaller than the outer peripheral side constricted portion 33pg toward the outer peripheral side (arrow c direction).

  The dust strip portion 5 is a lip portion that extends from the inner peripheral side (arrow d direction) end of the reinforcing ring 2 to the atmosphere side (arrow b direction) in the stroke direction (arrow ab direction) along the axis x. A convex lip tip 5a is formed on the inner peripheral side (in the direction of arrow d) of the dust lip 5 so as to slidably contact and seal with the outer peripheral surface 120a of the piston rod 120.

<Action and effect>
When the sealing device 1 having such a configuration is mounted between the piston rod 120 and the cylinder 110, the inner peripheral lip 32 of the seal lip portion 4 contacts the outer peripheral surface 120a of the piston rod 120 with an appropriate tightening allowance. Is done. Thereby, the sealing device 1 can prevent the hydraulic oil inside the cylinder 110 from flowing out from the outer peripheral surface 120a of the piston rod 120 to the atmosphere side (arrow b direction).

  When the sealing device 1 is mounted, as shown in FIG. 3, the inclined surface 336 of the protrusion 33 of the seal lip portion 4 comes into contact with the inner peripheral inclined surface 116 a of the protrusion 116 of the rod guide 115, and the protrusion 116, the protrusion 33 is pushed to the inner peripheral side (arrow d direction) in the radial direction (arrow cd direction) perpendicular to the axis x.

  In this case, the protrusion 33 bends so as to fall to the inner peripheral side (in the direction of arrow d) due to the presence of the neck portion 339, and the inner peripheral side end surface 334 of the protrusion 33 has a sealing target side of the rear surface 323 of the inner peripheral lip 32. It comes into contact with the end in the direction of arrow a. As a result, an annular space IC closed at the seal lip portion 4 is formed by the inner peripheral side constricted portion 33pi of the protrusion 33 and the rear surface 323 of the inner peripheral lip 32, and the rear surface 323 of the inner peripheral lip 32 is formed. It is concealed by the ceiling portion 331 of the protrusion 33.

  Accordingly, even when the hydraulic pressure of the hydraulic oil in the cylinder 110 increases in accordance with the operation of the piston rod 120 and the hydraulic pressure F is applied to the ceiling surface 332 of the ceiling portion 331 of the protrusion 33, the inner peripheral side The hydraulic pressure F is not applied to the inclined surface that is the back surface 323 of the lip 32.

  Therefore, unlike the prior art, a component force Fb (see FIG. 4) that presses the inner peripheral lip 32 against the outer peripheral surface 120a of the piston rod 120 by the hydraulic pressure F does not act, and the inner peripheral lip 32 and the piston It can suppress that a contact area with the outer peripheral surface 120a of the rod 120 increases. Thus, the sealing device 1 can stabilize the sealing performance by preventing the inner peripheral lip 101a from being worn and worn.

  Further, the sealing device 1 has the above-described effects due to the presence of the protrusion 33 integrally formed with the outer peripheral lip 31 and the inner peripheral lip 32 of the seal lip 4 without using the conventional backup ring 160 or the like. Therefore, it is possible to prevent a decrease in sealing performance and maintain a stable sealing performance with a simple configuration.

  Thus, the sealing device 1 having a simple configuration and low cost that can suppress an increase in the contact area between the inner peripheral side seal lip 32 and the outer peripheral surface 120a of the piston rod 120 can be realized.

<Other embodiments>
In the above-described embodiment, the case where the protrusion 33 is integrally formed adjacent to the inner peripheral lip 32 has been described. However, the present invention is not limited to this, and the inner peripheral lip 32 may be formed. If the back surface 323 can be concealed by the ceiling portion 331 of the protrusion 33, the inner peripheral lip 32 and the protrusion 33 may be formed separately.

  In the above-described embodiment, the case where the protrusion 33 is provided adjacent to the inner peripheral lip 32 as the seal lip has been described, but the present invention is not limited to this, and the outer peripheral side as the seal lip. The protrusion 33 may be provided adjacent to the lip 31, and the protrusion 33 may be provided on both the inner peripheral lip 32 and the outer peripheral lip 33.

  The preferred embodiment of the present invention has been described above. However, the present invention is not limited to the sealing device 1 according to the above-described embodiment, and all aspects included in the concept of the present invention and the claims. including. In addition, the respective configurations may be selectively combined as appropriate so as to achieve at least part of the above-described problems and effects. For example, the shape, material, arrangement, size, and the like of each component in the above embodiment can be changed as appropriate according to the specific usage mode of the present invention.

  The case where the sealing device of the present invention is applied to a hydraulic shock absorber of an automobile or a motorcycle has been described. However, the sealing device of the present invention is not limited to this, and is mounted between the piston rod and the cylinder, and is used for hydraulic buffering of various other vehicles and industrial machines that are affected by the hydraulic pressure in the cylinder. It can be used for a vessel.

DESCRIPTION OF SYMBOLS 1,100 Sealing device 2 Reinforcement ring 3 Elastic body part 4 Seal lip part 5 Dustrip part 5a Lip tip part 23 Fixed adhesion part 24 Lip support part 24a Inner peripheral surface 24b Outer peripheral surface 25 First dust lip 25s Lip tip part 26 Garter Spring 27 Recess 29 Second dust lip 31 Outer lip 31a Lip tip 32 Inner lip (seal lip)
33 Protruding part 33pg Outer peripheral side constricted part 33pi Inner peripheral side constricted part 110 Cylinder 115 Rod guide 116 Convex part 116a Inner peripheral side inclined surface 120 Piston rod (shaft)
120a Inner peripheral surface 321 Lip body portion 322 Lip tip portion 323 Rear surface 324 Ceiling surface 331 Ceiling portion 332 Ceiling surface 334 Inner peripheral end surface 335 Outer peripheral end surface 336 Inclined surface 339 Neck portion x Axis line

Claims (3)

An annular reinforcing ring centered on the axis;
An elastic body portion made of an annular elastic body formed integrally with the reinforcing ring around the axis.
The elastic body part is
An annular seal lip having a lip body extending in a direction along the axis, and a lip tip formed on the lip body so as to slidably contact an outer peripheral surface of a shaft to be sealed;
An annular protrusion provided adjacent to the seal lip and protruding in a direction along the axis;
The protrusion is
A ceiling portion having a flat ceiling surface parallel to a direction orthogonal to the axis;
The ceiling portion is supported in a direction along the axis, and the ceiling portion has a neck portion formed so as to be able to bend in a direction orthogonal to the axis.
When the ceiling portion of the protrusion is pressed toward the outer peripheral surface of the shaft, the ceiling portion bends in a direction perpendicular to the axis via the neck portion, and a part of the ceiling portion is A sealing device, wherein the sealing device is in contact with a back surface of the lip main body portion which is a back side of the lip tip portion. An annular space is formed between the ceiling portion and the lip body portion when a part of the ceiling portion is in contact with the back surface of the lip body portion, and the back surface of the lip body portion is concealed by the ceiling portion. The sealing device according to claim 1, wherein: 3. The sealing according to claim 1, wherein the elastic body portion includes a dust lip provided on the atmosphere side of the seal lip so as to slidably contact the outer peripheral surface of the shaft. apparatus.

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